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Geological and Paleontological Sites of Brazil

SIGEP 128 Talhado Canyon, Region, Northern State Outstanding Geomorphic Feature of a Complete Traverse of the Espinhaço Range

Mario Luiz de Sá Carneiro Chaves1 Leila Benitez2 Kerley Wanderson Andrade2 Marcos Aurélio Sartori3

1 Centro de Pesquisas Prof. Manoel Teixeira da Costa, Instituto de Geociências da Universidade Federal de Minas Gerais. Av. Antônio Carlos 6627. – MG. CEP 31.270-901. Pesquisador CNPq. E-mail: [email protected] . 2 Instituto de Geociências da Universidade Federal de Minas Gerais. Av. Antônio Carlos 6627. Belo Horizonte – MG. CEP 31.270-901. E-mails: [email protected] , [email protected] . 3 Biopreservação Consultoria Ltda. Rua José Apolinário Pena, 5. – MG. CEP 36.525-000. E-mail: [email protected] .

© Chaves,M.L.S.; Benitez,L.; Andrade,K.W.; Sartori,M.A. 2006. Talhado Canyon, Porteirinha Region, Northern Minas Gerais State - Outstanding Geomorphic Feature of a Complete Traverse of the Espinhaço Range In: Winge,M.; Schobbenhaus,C.; Berbert-Born,M.; Queiroz,E.T.; Campos,D.A.; Souza,C.R.G.; Fernandes,A.C.S. (Edit.) Sítios Geológicos e Paleontológicos do Brasil. Available on line 22/11/2006 at the address: http://www.unb.br/ig/sigep/sitio128/sitio128english.pdf [actually http://sigep.cprm.gov.br/sitio128/sitio128english.pdf]

(The above bibliographic reference of author copy right is required for any use of this article in any media, being forbidden the use for any commercial purpose)

Talhado Canyon, Porteirinha Region, Northern Minas Gerais State Outstanding Geomorphic Feature of a Complete Traverse of the Espinhaço Range SIGEP 128

Mario Luiz de Sá Carneiro Chaves1 Leila Benitez2 Kerley Wanderson Andrade2 Marcos Aurélio Sartori3

The Talhado Canyon is located in the Espinhaço Range, eastern of the Porteirinha town, in the northernmost part of the Minas Gerais State. This important geomorphic feature represents a unique natural traverse that totally cuts the Espinhaço Range in this State. The canyon was carved by the Mosquito River, along an east-west trending normal fault. The canyon exposes a record of slightly folded and metamorphosed sediments and volcanics of the Espinhaço Supergroup, which is composed in that region by five informal mapping units, from base to top: , Talhado, Gerais de Santana, Resplandecente, and Serra Nova units. This sequence was deposited in a rift type basin and was deformed during the Brasiliano Cycle (Neoproterozoic). Besides its geological and morphological aspects, the Talhado canyon has also an historical and social importance, once it has served during centuries as a passage to travelers, muleteers and donkeys of burden between the west (Porteirinha and Serranópolis de Minas counties) and the east ( county). Nowadays the canyon is inserted in an environmental protection area and so the ecotourism should be stimulated to turn public this outstanding geomorphological feature and the stratigraphic section of the Espinhaço there exposed.

Keywords: Talhado Canyon; Espinhaço Range; Porteirinha town; Minas Gerais.

INTRODUCTION aspects recommend the Talhado Canyon as a site of the Brazilian natural heritage to be preserved. The Espinhaço (back-bone) range, a noun given in the beginning of the nineteen century by the LOCALIZATION German mining engineer Baron Wilhelm von Eschwege, is a linear, relatively narrow and more than Porteirinha town is placed in the north extreme of one thousand km long north-south striking belt. The the Minas Gerais State, distant about 600 km from the range begins near the city of Belo Horizonte (central capital Belo Horizonte (Fig. 2). This distance can be part of the Minas Gerais State), and follows covered totally by asphalted roads; initially by road northwards crossing the whole Bahia State, until the BR-040 and after by road BR-135 in direction to borders of the Piauí State. In Minas Gerais the width , and towns, arriving finally to of the ridge is extremely variable between 60-80 km in the Porteirinha town. The Talhado Canyon is located the parallel of Diamantina, until about than 3 km in the small municipality of Serranópolis de Minas, width north of the Grão Mogol town. To the east of located 21 km from Porteirinha by a precarious land Porteirinha, in the northern extreme of Minas Gerais, road. The “entrance” of the canyon occurs 5 km east there is an 8 km width natural passage, the only one in from Serranópolis de Minas (42º48’W and 15º49’S). this State that crosses the Espinhaço Range side by side. This notable geomorphological and structural SHORT HISTORY feature known as “Talhado” (meaning carved or cut out) (Fig. 1 and 1A) is assigned as the Talhado The first habitants of Porteirinha region were Canyon. It represents an important feature not only adventurers searching gold deposits at the beginning by its geologic and morphologic characteristics and of the XVIII century. Although such diggings the beauty of its landscape, but also by its historical obtained no success, extreme areas were explored and and social interest, since it has joined during centuries a village named São Joaquim de Porteirinha was people of both sides of the range. Thus, all these established in the edges of the Mosquito River. 1

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Figure 1: View from west to east of the Talhado Canyon entrance, detaching the wall of the Espinhaço Supergroup quartzites in the western part of the range. Figure 1A: Detailed view of the initial stretch of the canyon, also showing the exuberant vegetation still preserved in the interior of this structural feature.

Porteirinha town was created only in 1937, by the mineral deposits at the western side of Espinhaço dismemberment of the lands of Grão Mogol county. Range (Drummond et al., 1980). In the 1990’s decade, Of recent creation the formerly named Serranópolis the Espinhaço Project (COMIG/UFMG agreement) district was emancipated of Porteirinha in 1997, with was centrated on the geological cartography and data the new name of Serranópolis de Minas. Like all this integration at scale 1:100,000 of the whole range in the region is very poor, the Talhados’s Canyon has been Minas Gerais State, and the focused area is a part of an way of passage to travelers and troop of donkeys the Rio Pardo de Minas map sheet of this project with provisions between Porteirinha and Serranópolis (Roque et al., 1996). The stratigraphy of the de Minas towns with the other (east) side of the Espinhaço Supergroup is actually object of detail Espinhaço Range, in direction to small villages as studies (preliminary results in Chaves et al., 2005). Nova Aurora, Rio Peixe Bravo, Curralinho, etc., in the Rio Pardo de Minas county. Geomorphological Context

DESCRIPTION OF THE SITE The region of Porteirinha–Serranópolis de Minas, to the west of the Espinhaço Range, is inserted in the The Espinhaço Range in the northern extreme of “Edges of the Espinhaço Plateau” which is enclosed Minas Gerais State is still bad known concerning to in the “Domain of Crystalline Plateaus”, according to geological aspects. First studies in this region are due Mauro et al. (1982). These plateaus constitute to Schobbenhaus (1971, 1972) that mapped a long transition belts separating units situated in different interval of the range between Porteirinha and Monte topographical levels, and thus forming a topographical Azul towns, the last one near the frontier of the Bahia platform between the range and the lowest areas. The State. At the end of the 1970’s decade a climate is tropical half-dry to dry and the vegetal DNPM/CPRM agreement carried out the covering integrates different types, where species of Porteirinha– Project aiming the search of savannah and stational forest predominates. In 2

______Geological and Palaeontological Sites of Brazil general, the relief reveals considerably dissected, with metaconglomerates (Gerais de Santana Unit), while the development of an intense net of draining, mainly the ridges are supported by quartzites. the west of the range in the domain of the Crystalline Basement. In the range zone, the “Espinhaço Plateau” present steps sculptured in quartzitic rocks, with altitudes that vary between 700 and 900 m, occurring a peak that is raised up to 1,465 m.

Espinosa 45° 43° Monte Azul

Porteirinha

Janaúba Serranópolis

2 2 Salinas

1 BR-116 - 1 G 25 M R- B Montes Grão Claros Mogol

17° 17° Bocaiúva

5 3 -1 R B Buenópolis

Três Marias MG Figure 3: Landsat 7/TM+ satellite image showing in its

a i

l Belo central part the east-west oriented canyon in the Espinhaço í

s Horizonte a

r Range formed by the Mosquito River (Source: B www.embrapa.gov.br, 2004, Brazil Seen from the Space). Curvelo B R 19° -0 4 050100 km The metamorphic basement was uplifted by the 0 19° Paraopeba cretaceous epeirogeny and the resulting faults represent a reactivation of older Precambrian

BELO HORIZONTE inherited fault lines. It is admitted that the planning surfaces formed during this uplift are the result of the 45° 43° São Paulo Vitória action of morphogenetic processes truncating Figure 2: Location map and access to Porteirinha – different lithologies and/or superimposed structures. Serranópolis de Minas region (State of Minas Gerais). Thus, the feature known as “Talhado” represents a canyon formed by the Mosquito River throughout a According to King (1956), such steps belong to normal fault that cuts the units of the Espinhaço different planning surfaces. The west of the mountain Supergroup (Fig. 3). The scarps of the canyon show range, the surface leveled between 600-700 m superimposed structures, like folds and small faults. integrates the “Velhas Surface”, while the range Altitude variations that define different steps are well platforms between 850-950 m and 1,200-1,300 m shown along the valley of the Mosquito River. In the compose distinct surfaces developed in the range zone more elevated plans, a ruin-shaped landscape is represented, respectively, by the “South American” observed, as well as the presence of great isolated and “Post-Gondwana” surfaces of this author. The boulders. high ridges are conditioned by the structure of the The development of the Talhado Canyon Espinhaço, with pattern marked for by tiltings and throughout geologic time is associated to different faults, responsible for the morphology of the relief periods of staging of the above mentioned characterized by canyon-shaped valleys and sharp geomorphological evolution. The Mosquito River scarps. In the same context, the Espinhaço belongs to the basin of the São Francisco River and Supergroup includes at its base acid and intermediate has its springs in 1,300 m of altitude, in the area of lava flows and intrusions (Mato Verde Unit), with “Gerais de Santana”, flowing firstly about 10 km in variations in the lithologic composition and resistance north-south direction between quartzite ridges. After to erosion, having as result several peaks that put in this river forms a curve of 90° to take the east-west evidence synclinal and anticlinal structures and others direction, resulting in the development of the canyon. of circular aspect. The biggest valleys of north-south One suggests that the processes of epeirogenic uplift direction had been sculptured in more susceptible that had led to the formation of the range, were more rocks to the erosion as phyllites, soft quartzites and intense or were submitted to posterior reactivations to 3

______Geological and Palaeontological Sites of Brazil the east side of the range, in the contact zone of the Espinhaço rocks covered in conformity by the Espinhaço Supergroup with the Macaúbas Group. Macaúbas Group. The width of the Espinhaço Range The north-south striking part of the river probably ran in the region is about 8-10 km while in the initially to the east, in direction to the basin of the diamondiferous district of Grão Mogol, to south, its Pardo River (only about 700 m separates the two width is lesser than 7 km. In the same way, the basins). The mentioned uplift caused the capture of (volcano) sedimentary sequence is very thicker in the the east-west arm of the Mosquito River, so allowing focused area with 1,000 m against 300 m in the Grão the increasing of the erosion along the fault and Mogol region. originating the canyon.

Figure 5: Proposed stratigraphic section of the Espinhaço Supergroup along the Talhado Canyon.

According to Chaves et al. (2005) five units are recognized in the Espinhaço Supergroup, informally named from base to top Mato Verde, Talhado, Gerais de Santana, Resplandecente and Serra Nova units, with N-S strike trends (Fig. 4 and 5). Additional

studies also have been conducted aiming the Figure 4: Geology of the Serra do Espinhaço in formalization of the mentioned units and the Serranópolis de Minas region, eastern of Porteirinha town correlation with other lithostratigraphic units of the (State of Minas Gerais). Espinhaço Supergroup that occur both to the south (Grão Mogol- areas) and to the north Geology (Southern Bahia State).

At the western side of the range, the Espinhaço MATO VERDE UNIT Supergroup is covering on angular and erosive discordances granitic and gneissic rocks of the This unit occurs in the western border of the Basement Complex, while at the eastern side the range, enclosing metavolcanic rocks associated with 4

______Geological and Palaeontological Sites of Brazil metaconglomerates that mainly occur at east of the Canyon presenting magnificent outcrops. This unit Mato Verde town (north of Porteirinha). Some has a special geomorphology showing quartzite with scattered outcrops of the unit also occur to the south, long parallel crests divided by flat valleys in disappearing completely after crossing the Mosquito concordance with the structural N-S trend. Primary River, when the upper stratigraphic units (Talhado sedimentary structures are metric plan-parallel levels and Gerais de Santana) form the basal portion of the separated by ripple mark horizons (Fig. 6), and supergroup. Thus, in the Talhado Canyon, the Mato assyntotic cross stratifications of small size. The ripple Verde unit is only a few meters thick, while to the marks are more frequent to the top of the unit, north it can reach about 50 m, allowing its division in pointing out the thinning of the beds in this direction. two levels. The basal level is composed by polymictic The complete estimated thickness is between 350 to metaconglomerate with (rare) associated arcosian 400 m. Rocks and sedimentary structures indicate to a schist. Clasts of gneiss, migmatite, metabasic rock and coastal to shallow marine environment. vein quartz can reach 25 cm in diameter, generally with angular to subrounded forms, and a phyllitic or GERAIS DE SANTANA UNIT schistose gray, iron oxide-rich matrix. The upper level encloses acid and intermediate volcanic rocks with A sudden reducing in the relief can be observed interbedded pyroclastic rocks. In the first class occur to east of the Talhado Unit based on aerophotos and rhyolite, dacite, and rhyodacite, while in the other satellite images (Fig. 3). Field works showed that such class are found andesitic lavas with associated change is determined by the presence of more soft tuffaceous rocks. rocks like coarse quartzites, phyllites and metacoglomerates (Fig. 7). The designation Gerais de Santana was based on the name given to a planned area at southwestern of Serra Nova, a small village pertaining to the Rio Pardo de Minas County. In this area, a series of narrow folds caused enlarging of the unit to 4-6 km against 1 km verified in the Talhado Canyon section. The total thickness of the unit is between 150 and 200 m. Lithologies and primary sedimentary features, as channel cross stratifications, point out to an original alluvial environment.

Figure 6: Oscillation ripple marks that separate in the top distinct levels of the Talhado Unit, outcropping in the initial Figure 7: Metaconglomeratic level (Gerais de Santana western part of the Talhado Canyon, in the Mosquito River Unit) with rounded clasts preferentially of quartz vein. margins. These conglomerates constitute the source rock of diamonds in the region (outcrop in the confluence of the TALHADO UNIT Água Fria stream with the Mosquito River).

Placed over the Mato Verde metavolcanics, this RESPLANDECENTE UNIT unit is characterized by fine and pure quartzites, rarely micaceous, and thin intercalations of ferruginous The Resplandecente term was firstly used by quartzites. Locally this unit occurs directly over the Karfunkel and Karfunkel (1976) as a formation that is Basement Complex, like for example at southeastern characterized by fine and micaceous, white to red of the Serranópolis de Minas town. The Talhado quartzites occurring as fine beds in the Itacambira designation was proposed in reference to the Talhado region (Resplandecente mountain). Such rock type 5

______Geological and Palaeontological Sites of Brazil was also recognized in the Grão Mogol region by orogeny that folded the volcano-sedimentary sequence Chaves et al. (1999), when the unit had been of this basin only occurred in the neoproterozoic considered as a stratigraphic index-level for the whole during the Brasiliano Cycle (eg., Dussin and Dussin, northern belt of the Espinhaço Range in Minas 1995). A main regional phase of folding was Gerais. Similar rocks were mapped in the southern responsable for the formation of synclinal and part of the study area on the Gerais de Santana Unit. anticlinal folds with north-south axis and west However, such rocks are restricted to the Talhado vergence in direction to the São Francisco Craton. area. Beyond the granulometry and texture of the The result structures of this phase are shear zones quartzites, another characteristic of these rocks is the (ductile domain) and thrust faults (ductile-ruptile presence of small, medium, and large tabular cross domain) with west direction. In the Porteirinha area stratifications along the whole 200 m thick section of the Espinhaço Supergroup presents a homocline the unit, that can be interpreted as of eolic origin, structure showing low to medium dip values to east. probably in a seashore context. In north direction, at west of Monte Azul and Espinosa towns (MG) and Guanambí town (BA), the SERRA NOVA UNIT Central and Palmas do Monte Alto mountains show dips to west, indicating that in Porteirinha region the This unit occurs continuously at the earstern side other flank of this megastructure has been eroded. of the range, forming a quartzitic horst that is limited Gravity faults (ruptile domain) are associated to a late, to east by eroded Macaúbas Group rocks. The Serra not much intense folding phase that refolded the Nova designation has been taken from the name of north-south axis generating brachyanticline and the small village where excellent outcrops of the unit brachysyncline structures. The Talhado Canyon is occur. At this village begins a long track through the related to this last fault type (Fig. 9), that also enclosed highlands crossing the range from east-west (Fig. 4). rocks of the Basement Complex at the western side of The Serra Nova Unit is composed by fine, white the range. quartzites with plane-parallel stratifications and giant cross stratifications (Fig. 8). At west the contact with the Resplandecente Unit is gradational, while at east an erosive contact with the Macaúbas Group is being object of specific investigation. The estimated thickness ‘of this sedimentary unit is of 200 m, deposited in eolic environment, possibly under desert conditions.

Figure 9: Detail of the western initial part of the canyon crossing the quartzite sequence (Talhado Unit), showing the approach W-E direction of the normal fault that generated the structure.

PRESERVATION MEASURES

The Espinhaço Range presents a landscape of Figure 8: Cross stratification of great dimension in rare beauty in which isolated hills and mounts, quartzites of the Serra Nova Unit in the top of the profile waterfalls, steep valleys and typical vegetation with located in Talhado Canyon. extremely specialized floristics varieties can be observed and appreciated. In consequence, the Tectonic evolution and the canyon formation majority of the towns related to the Espinhaço have looked for to establish norms of environmental Actually most authors consider that the control or protection in areas located over the range sedimentation and associated volcanism of the and at its borders. One of the first units of Espinhaço basin has been developed in a north-south conservation with integral protection in this mountain striking rift valley from late Paleoproterozoic (±1,75 range was the National Park of the Serra do Cipó, Ga) until the Mesoproterozoic (1,4 Ga). However, the created at 1984 year. Since then, several other units of 6

______Geological and Palaeontological Sites of Brazil conservation had been created along the mountain will enclose areas of the counties of Porteirinha, Mato range with objective to preserve the biodiversity of the Verde, Monte Azul and Rio Pardo de Minas. region. Recently, in 2005, the UNESCO recognized Preliminary studies indicate the presence of four the Espinhaço as a reserve of the biosphere for species that integrate the "Red Book" of the sheltering innumerable species of the threatened fauna threatened species extinguishing flora of Minas Gerais and the flora of extinguishing. This recognition opens (Mendonça and Lins, 2000) beyond several other new perspectives for conservation through the endemic and/or restricted species. Although having in partnership of biodiversity, geodiversity and economic mind its extremely privileged landscape shown by the development. forms the relief (Fig. 11), the crystalline water springs, Moreover, the social importance of the Talhado the vegetation, and a relatively mild climate, the region Canyon must be enhanced as it constitutes a natural needs sustainable development strategies focusing the landscape that has served as communication route tourism, the commerce of handicrafts, recreation through the two edges of the mountain range (Fig.10). clubs, hotel net, etc. Such aspects will contribute to ecotouristic activities easily developed in the regional economy and are the way to stimulate the environment preservation.

REFERENCES

Chaves,M.L.S.C.; Karfunkel,J.; Addad,J. 1999. Geologia da região diamantífera de Grão Mogol (MG). Geociências, 18:129-155. Chaves,M.L.S.C.; Egger,V.A.; Dussin,T.M. 2005. Diamantes na Serra do Espinhaço entre Serranópolis e Mato Verde (MG): base geológica. In: Simpósio Brasileiro de Geologia do Diamante, 4, Anais do..., Diamantina, p.31-34. Figure 10: Aspect of the passage of the Talhado Canyon Drumond,J.B.V.; Von Sperling,E.; Raposo,F.O. 1980. showing handle-of-steel affixed at a thick wall of quartzite Projeto Porteirinha - Monte Azul. Belo Horizonte, (Talhado Unit), so that the people can hold themselves Convênio DNPM/CPRM, Relatório Final, vol. 1, during sudden torrents. 550p. Dussin,I.A.; Dussin,T.M. 1995. Supergrupo Espinhaço: modelo de evolução geodinâmica. Geonomos, 3:19-26. Karfunkel,B.; Karfunkel,J. 1976. Geologia da Serra do Espinhaço no norte de Minas Gerais (Itacambira – ). In: Congr. Bras. Geol., 29, Ouro Preto, Anais do..., p.169-177. King,L.C. 1956. A geomorfologia do Brasil Oriental. Revista Brasileira de Geografia, 18:147-265. Mauro,C.A.; Dantas,M.; Roso,F.A. 1982. Geomorfologia. In: Projeto Radambrasil, Folha Brasília, v.29, p.253- 258. Mendonça,M.P.; Lins,L.V. 2000. Livro Vermelho das espécies ameaçadas de extinção da flora de Minas Gerais.

Belo Horizonte, Fundação Biodiversitas-Fundação Figure 11: Image of the Espinhaço Range showing in its Zoobotânica de Belo Horizonte, 223p. central part the Talhado Canyon, at a cold morning of July, Roque,N.C.; Guimarães,M.L.V.; Noce,C.M.; in which clouds are totally concentrated over the mountain Knauer,L.G.; Grossi-Sad,J.H. 1996. Projeto Espinhaço range. – Folha Rio Pardo de Minas. Belo Horizonte, Convênio COMIG/IGC-UFMG, 1 folha. The region still shelters part of the State Park of Schobbenhaus,C. 1971. Mapa geológico da Serra do Serra Nova (located in the Rio Pardo de Minas Espinhaço entre Porteirinha e Monte Azul, norte de Minas county) and the Serrado Environment Protection Gerais. Recife, Ministério do Interior, SUDENE, 1 Area (located in the Porteirinha county), both at north mapa (Escala 1:120.000). of the canyon. New studies are being carried out Schobbenhaus,C. 1972. Geologia da Serra do Espinhaço aiming to create the National Park of the Serrado that entre Porteirinha e Monte Azul, norte de Minas Gerais. 7

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Recife, Ministério do Interior, SUDENE, Relatório Interno, 19p. (Inédito). Uhlein,A.; Trompette,R.R.; Egydio-Silva,M. 1986. Estruturação tectônica do Supergrupo Espinhaço na região de Diamantina (MG). Revista Brasileira de Geociências, 16:212-216.

1 Centro de Pesquisas Prof. Manoel Teixeira da Costa, Instituto de Geociências da Universidade Federal de Minas Gerais. Av. Antônio Carlos 6627. Belo Horizonte – MG. CEP 31.270-901. Pesquisador CNPq. E-mail: [email protected].

2 Instituto de Geociências da Universidade Federal de Minas Gerais. Av. Antônio Carlos 6627. Belo Horizonte – MG. CEP 31.270-901. E-mails: [email protected], [email protected].

3 Biopreservação Consultoria Ltda. Rua José Apolinário Pena, 5. Guiricema – MG. CEP 36.525-000. E-mail: [email protected].

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